System and method for sending data to a mobile device in a wireless network

ABSTRACT

A device for wirelessly transmitting data under a wireless protocol is contemplated. A remote wireless network device initiates a session with a network. In this manner, information is sent to a gateway associated with the access point that couples the remote wireless network device to the network. When the remote wireless network device moves, data is tunneled between the succeeding gateway and the original gateway, but for those sessions opened at the original gateway. Any sessions associated with the remote wireless network device at the new gateway are processed and maintained by the new gateway without tunneling the data.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority based on provisional application Ser.No. 60/443,114, entitled “System and Method for Sending Data to a MobileDevice in a Wireless Network” by Hilton Hung filed on Jan. 27, 2003.

FIELD OF THE INVENTION

The present invention relates to a wireless communication system. Moreparticularly, the present invention is related to sending data to anon-static device coupled to a wireless network.

BACKGROUND

In some wireless networks, an access point (AP) can be coupled to avariety of wireless network devices. Typically, a wireless network canallow a mobile device to send and receive data as it moves throughcoverage zones of the individual access points. Sometimes, the wirelessnetwork device will initiate a session with a particular gateway. Thedata that is transferred to the wireless network device is sent to thegateway, which then relays the data to the wireless network device.Relatedly, the data emanating form the wireless network device is sentto the initial gateway, from where it is relayed to the ultimatedestination.

When the wireless network device is mobile, the wireless network devicecan leave the coverage zone of a particular access point, or associatedgateway. The wireless network device reinitiates contact with an accesspoint that services the new location where the wireless network deviceis now located. In this manner, a new gateway may be used for thecommunication of information to and from the wireless network device.

In many cases, a link between the old gateway and the new gateway isestablished. Data traffic to the wireless network device is received bythe old gateway, encapsulated by the old gateway, and relayed to the newgateway. At the new gateway, the data is decapsulated, and sent to thewireless network device.

Data traffic from the wireless network device is handled in much thesame way. Data from the wireless network device is relayed from thewireless network device to the current gateway. The current gatewayencapsulates the data and relays it to the original gateway. At thispoint, the original gateway decapsulates the data and relays it to theultimate destination.

This paradigm is used for ongoing sessions, as well as new sessions.Thus, when the wireless network device starts a link at the newlocation, the encapsulation and relaying of the data from the newgateway to the original gateway is undertaken.

In this manner, a single gateway acts as the central point for allcommunications to and from a particular wireless network device. Thetransferring of the data to a new gateway takes additional time andeffort, especially when the wireless network device is operating withseveral open sessions.

Such a mechanism may be found in the use of Mobile IP, a proposal beforethe Internet Engineering Taskforce (IETF). Mobile IP involves the use ofa “Home Agent”, which is the location of the device's known IP address,and a “Foreign Agent”, which knows the actual location of the device.All traffic intended for the device is sent to the Home Agent and isthen “tunneled” to the Foreign Agent for delivery to the device. Thissame type of method can be used within a wireless LAN, without the needto use the Mobile IP protocol.

In a more trivial implementation of a tunneling system to achieveseamless subnet roaming, an administrator could be forced to assign a“Home” Gateway for each wireless user in the network. Each wirelessclient would then communicate to its currently local access point, whichwould “tunnel” the packet to the client's “Home” Gateway. However, thisimplementation has two major inefficiencies. First, it requires theadministrator to setup a Home Gateway for each user. Secondly, and moredifficult to work around, it is rather inefficient, forcing more trafficto be tunneled than necessary

SUMMARY

A device for wirelessly transmitting data under a wireless protocol iscontemplated. A remote wireless network device initiates a session witha network. In this manner, information is sent to a gateway associatedwith the access point that couples the remote wireless network device tothe network. When the remote wireless network device moves, data istunneled between the succeeding gateway and the original gateway, butfor those sessions opened at the original gateway. Any sessionsassociated with the remote wireless network device at the new gatewayare processed and maintained by the new gateway without tunneling thedata.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated into and constitute apart of this specification, illustrate one or more embodiments of thepresent invention and, together with the detailed description, serve toexplain the principles and implementations of the invention.

In the drawings:

FIGS. 1 through 3 are network diagrams detailing the mechanics awireless network with a dynamic gateway system, according to theinvention.

DETAILED DESCRIPTION

Embodiments of the present invention are described herein in the contextof a System And Method for Sending Data to A Mobile Device in A WirelessNetwork. Those of ordinary skill in the art will realize that thefollowing detailed description of the present invention is illustrativeonly and is not intended to be in any way limiting. Other embodiments ofthe present invention will readily suggest themselves to such skilledpersons having the benefit of this disclosure. Reference will now bemade in detail to implementations of the present invention asillustrated in the accompanying drawings. The same reference indicatorswill be used throughout the drawings and the following detaileddescription to refer to the same or like parts.

In the interest of clarity, not all of the routine features of theimplementations described herein are shown and described. It will, ofcourse, be appreciated that in the development of any such actualimplementation, numerous implementation-specific decisions must be madein order to achieve the developer's specific goals, such as compliancewith application- and business-related constraints, and that thesespecific goals will vary from one implementation to another and from onedeveloper to another. Moreover, it will be appreciated that such adevelopment effort might be complex and time-consuming, but wouldnevertheless be a routine undertaking of engineering for those ofordinary skill in the art having the benefit of this disclosure.

In accordance with the present invention, the components, process steps,and/or data structures may be implemented using various types of digitalsystems, including hardware, software, or any combination thereof. Inaddition, those of ordinary skill in the art will recognize that devicesof a less general purpose nature, such as hardwired devices, fieldprogrammable gate arrays (FPGAs), application specific integratedcircuits (ASICs), or the like, may also be used without departing fromthe scope and spirit of the inventive concepts disclosed herein.

FIGS. 1 through 3 are network diagrams detailing the mechanics awireless network with a dynamic gateway system, according to theinvention. A wireless network 10 contains several functional units.These include gateways 12, 14, and 16. Access points 18 and 20 arecoupled to the gateway 12. Access points 22 and 24 are coupled to thegateway 14, and an access point 26 is coupled to the gateway 16.

Assume that a wireless network device 28 makes contact with the accesspoint 26. After making a network connection, the information for aparticular session 30 initiated while in the zone serviced by the accesspoint 26 is sent through the gateway 16. The date flow from the networkis indicated by the arrow 40, and the data flow from the gateway 16 tothe access point is indicated by the arrow 42.

In FIG. 2, assume that the wireless network device 28 then moves to thezone serviced by the access point 24. For the information traveling tothe first session 30, the gateway 16 encapsulates the data and relays itto the gateway 14. This is indicated by the arrow 44. From there thegateway 16 relays that information to the device 28, denoted by thearrow 46.

In FIG. 3, assume that the wireless network device 28 initiates a secondnetwork session 32. The wireless network device 28 requests the newsession 32 through the gateway 14. However, instead of sending the databound for the session 32 and to the gateway 16, the gateway 14 assignsan address to the session so that the gateway 14 can directly servicethe second session 32. This is denoted by an arrow 48. Thus, the pathwayfor information for the second session 32 flows directly through thegateway 14, rather than being sent to the gateway 16, beingencapsulated, and then sent to the gateway 14 for final delivery to thesession 32.

In this manner, the gateway that initiates a network session from anetwork device may be thought of as an agent for the particular session.The gateways that the wireless network device 28 may move to will be theforeign agents for the session. Thus, when the wireless network device28 moves, the new gateway will not have to encapsulate and deliver everysingle transmission emanating from the wireless network device 28 to acentral gateway responsible for that client. The new gateway can sendand deliver data directly to the wireless network device 28 for thosesessions the new gateway initiates during the time under its aegis,rather than have another gateway encapsulating and forwarding the data.

Of course, the flow of data going from the network device 28 to thenetwork can be treated in a similar manner. Thus, instead of the newgateway encapsulating and forwarding data to another gateway, the newgateway can initiate a direct link to the network for those sessionsstarted on the network device 28 while that device is under the aegis ofthe new gateway.

In a more detailed example assume that a client device associates withan access point. In this case, it might use address resolution protocol(ARP) and dynamic host communication protocol (DHCP) service to requestan internet protocol (IP) address from the network. The initial gatewayresponds to such a request using a pool of IP addresses it has beenassigned (either through prior assignment, or through any othermechanisms.)

When the client has an IP address, it can then begin an application thatrequires a high layer connection, such as, for example, a transportcontrol protocol (TCP) application. Such an application might be thoselike an email application, a file sharing application, or a web browsingapplication, just to name a few.

If the client device moves to any of the other access points connectedto the original gateway, only a reassociation process need take place.Other network information (like IP address, default gateway, etc.) isstill valid for this access point.

When the client device roams from an access point attached to the firstgateway to an access point attached to a different gateway, it ispreferable to accomplish this without breaking the higher layer (e.g.TCP) connection. The gateways can inform each other that the move hasoccurred.

In addition to simple notification, gateways in adjacent physicallocations can be kept appraised of the clients currently attached toeach other. In this way, roaming can be anticipated, and the transfer ofinformation between the gateways expedited.

In the current implementation, data from the network intended for theclient continues to be routed to the original gateway. Upon receipt ofthe data, the original gateway forwards them to gateway that the clientis now attached to. This second gateway then prepares the data for finaldelivery to the client.

When a client moves to a new subnet, or to a portion of network that iscontrolled by a different gateway, the network traffic operates for theongoing sessions in the above-mentioned manner. Thus, when a userestablishes a TCP session and then roams to a new subnet, the traffic istunneled, in both directions between the original gateway and the newgateway.

However, in the context of the current specification, such tunneling isonly carried out on an as-needed basis. The current specification offersrouting optimization for mobile networking. This optimization isachieved since only the traffic from particular sessions is tunneledbetween gateways.

In this context, assume that the client device associates with theoriginal gateway and starts a network application session. The clientthen moves to an access point attached to another gateway. When theclient device moves to the new access point, it cannot receive a new IPaddress without breaking its ongoing application session. Thus, thegateways establish a tunnel for the traffic associated with thisapplication session.

Assume that, when attached to the new access point, the client devicestarts a second network application session. The data associated withthis new network application session is allowed to pass directly out tothe network.

In one embodiment, the gateways map the original IP address of theclient device to a new IP address on a per-session basis. That is,traffic from one session, using the original IP address, is tunneledback to the gateway. However, traffic from the new session, using a newIP address, can be routed directly to and from the network.

1. A device for sending data to one or more wireless devices in awireless network, the data being time constant digital data, the devicecomprising: a first circuit for alerting the wireless devices that thetime constant digital data is to be sent; a second circuit for defininga frame in which the time constant digital data is to be sent; and athird circuit for sending the digital data to the one or more wirelessdevices.
 2. A device for sending data to a plurality of wireless devicesin a wireless network, the data being time constant digital data, thedevice comprising: a first circuit for alerting the wireless devicesthat the time constant digital data is to be sent; a second circuit fordefining a frame in which the time constant digital data is to be sent;and a third circuit for sending the digital data as a single data blockto the plurality of wireless devices within the frame.
 3. A device forreceiving data at one of a plurality of wireless devices in a wirelessnetwork, the data being time constant digital data, the devicecomprising: a first circuit for receiving an alert that the timeconstant digital data is to be sent; a second circuit for receivingparameters regarding a frame in which the time constant digital data isto be sent; a third circuit for receiving the digital data as a singledata block to the plurality of wireless devices within the frame; and afourth circuit for extracting the digital data bound for the one of aplurality of wireless devices from the single block of data.
 4. A devicefor receiving data from one or more wireless devices in a wirelessnetwork, the data being time constant digital data, the devicecomprising: a first circuit for alerting the wireless devices that thetime constant digital data is to be sent; a second circuit for defininga frame in which the time constant digital data is to be sent; a thirdcircuit for polling the particular wireless device to initiate thesending of the digital data; and a fourth circuit for receiving the datasent from each particular polled wireless device.
 5. A method forreceiving digital data from a wireless device in a wireless network, themethod comprising: alerting the wireless device to send the timeconstant data; polling the wireless device to send the time constantdata; and receiving a sent packet of time constant data from theparticular wireless device.
 6. A method for sending digital data from awireless device in a wireless network, the method comprising: awaitingan Alert to send the time constant data; subsequent to the alert,awaiting a Poll to send the time constant data; sending a sent packet oftime constant data from the particular wireless device.
 7. A method forsending digital data to a plurality of wireless devices in a wirelessnetwork, the method comprising: alerting the plurality of wirelessdevices to receive the time constant data; and sending one block ofdata, the one block of data comprising all of the data destined for theplurality of wireless devices.